Drinking too much coffee may be linked to an increased risk of osteoporosis, according to the latest research by the University of South Australia.

Investigating the effects of coffee on how the kidneys regulate calcium in the body, researchers found that high doses of caffeine consumed over six hours almost doubled the amount of calcium lost in the urine.

This is the first study to report the impact of high-dose, short-term caffeine intake on renal clearance of calcium, sodium, and creatinine in healthy adults.

UniSA’s Dr Hayley Schultz says with the emergence of an increasing ‘coffee culture’, it’s important for people to understand the impacts of what they are putting into their bodies.

“Caffeine is one of the most widely used recreational drugs in the world, with 80 per cent of adults consuming at least one caffeinated beverage per day,” says Dr Schultz.

“It’s a common stimulant, consumed by professionals, parents, shift workers, and teenagers alike to start their day and stay alert – even the military use caffeine to help combat sleepiness.

“But while coffee has its perks, it’s also important to acknowledge its fallbacks – one of them being how our kidneys handle calcium.

“Our research found that people who consume 800 mg of caffeine over a typical working day will have a 77 per cent increase in calcium in their urine, creating a potential deficiency that could impact their bones.”

Osteoporosis is a chronic, painful, and debilitating disease which decreases bone density and increases fracture risk. The condition occurs when bones lose calcium and other minerals faster than the body can replace them and is more common in women.

In Australia, an estimated 924,000 people have osteoporosis, a chronic, debilitating disease that occurs when bones lose calcium and other minerals faster than the body can replace them. As a result, bones become less dense and more susceptible to fracture.

Participants in the double-blind clinical study chewed caffeine or a placebo gum for five minutes at two-hour intervals over a six-hour treatment period (total caffeine 800 mg). Originally designed to examine the impact of caffeine on wakefulness, the sub-study evaluated the impact of caffeine consumption on the renal clearance of calcium.

Co-researcher UniSA’s Dr Stephanie Reuter Lange says understanding the long-term impacts of high caffeine consumption is especially important for higher-risk groups.

“The average daily intake of caffeine is about 200 mg – roughly two cups of coffee. While drinking eight cups of coffee may seem a lot, there are groups who would fall into this category,” says Dr Reuter Lange.

At-risk groups include teenagers who binge-consume energy drinks while bones are still developing, professional athletes who use caffeine for performance enhancement and post-menopausal women with low blood calcium levels due to hormonal changes, explains Dr Reuter Lange.

“Increasingly, we are also seeing high levels of caffeine among shift workers who need to stay alert over the nighttime hours, as well as those in the military who use caffeine to combat sleep deprivation in operational settings.

“Caffeine in moderation certainly has its pros. But understanding how excess consumption could increase the risks of highly preventable diseases such as osteoporosis is important.”

Sydney-based physiotherapist Dane Ford says while the results show interesting insights, 800mg of caffeine is much more than the average person would consume daily.

“The caffeine which the participants of this study consumed would equate to around eight to ten cups of coffee in six hours.

“To maintain or improve bone health, there are several things we can do.

“Ensure adequate calcium and protein intake, safe exposure to sunlight as a source of vitamin D, maintain a healthy weight, quit smoking, avoid excessive alcohol consumption, and regularly participate in progressive resistance training,” says Mr Ford.

Researchers hope to inform Australian dietary guidelines through further research into the impact of different levels of caffeine intake on short- and long-term bone health.